The invention relates generally to apparatus and methods for cutting sheet material and deals more particularly with an automatic cutting apparatus and method using a heated cutting blade for cutting piled or fleecy material, such as velour, made of thermoplastic fibers.
Automatic cutting apparatuses and methods are widely used today in the garment, automobile and furniture industries where much fabric is cut. Many of the cutting apparatuses are numerically controlled and are capable of cutting large quantities of pattern pieces from layups of sheet material with high speed and accuracy. For example, numerically controlled apparatuses are shown in U.S. Pat. Nos. 3,955,458 issued Sept. 17, 1973; 3,830,122 issued Aug. 20, 1974; and 4,091,701 issued May 30, 1978; each to Pearl and assigned to Gerber Garment Technology, Inc. of East Hartford, Conn. and hereby incorporated by reference as part of the present disclosure. Such numerically-controlled apparatuses may include a vertically-mounted reciprocating cutting blade, a horizontal bed for supporting the layup and a computer program to direct the cutting blade to cut the layup along a desired path to form the pattern pieces.
To insure cutting accuracy, it is often advantageous to positively affix the layup to the support bed while the layup is being cut and, if possible, compress the layup as disclosed in U.S. Pat. Nos. 3,495,492 issued Feb. 17, 1970; 3,790,154 issued Feb. 5, 1975; and 3,765,289 issued Oct. 16, 1973; each to Gerber et al and assigned to Gerber Garment Technology, Inc., and hereby incorporated by references as part of the present disclosure. As further disclosed in these patents, the layup may be covered with a substantially air-impermeable sheet, and a vacuum may be applied to the underside of the air-impermeable sheet to draw the impermeable sheet toward the support bed to fix and compress the layup while it is being cut.
Problems have emerged in the cutting of layups of piled or fleecy material, such as velour or velvet made of a carrier sheet and pile fibers attached to the carrier sheet, especially when the layups are compressed during cutting and the pile fibers have a significant length, such as one-thirty-second to one-eighth of an inch or more. During such compression, each work sheet is flattened under the pressure exerted by the sheet above and the free ends of the pile fibers are generally bent downwardly towards the carrier sheet. Consequently, many of the pile fibers invariably cross the path of the cutting blade as the layup is cut and portions of such pile fibers are cut off and freed from the remainder of the worksheet. When the cutting operation is complete, the bundles of pattern pieces are usually transported to a subsequent work site and during this transportation many of the free cut fiber portions may fall loose from the bundle as dust. This dust is unsightly, may lodge in machinery and is generally objectionable in many other ways.
In other types of cutting apparatuses layups of piled or fleecy sheets may be cut without a holddown or compression system. In such an arrangement, many of the pile fibers are cut but the number cut is usually fewer than the number cut by a cutting apparatus using holddown and compression, because the pile fibers in a non-holddown system are bent less during the cutting process than in the vacuum holddown system described above and therefore fewer pile fibers cross the path of the cutting blade. Also, if dies are used to cut a layup of piled or fleecy sheet material, pile fibers crossing the line of cut may be cut to create pile dust. Even if a single sheet of such material is cut by a reciprocating knife or die without a holddown system some pile fibers are cut although usually much fewer than are cut from a sheet in a layup of such material cut under compression.
The pile fibers and/or carrier sheets of piled or fleecy work sheets, such as velours, are often made of polyester or other thermoplastic material, as for example in the case where the pattern pieces are to be used for making automobile seats or other objects requiring highly-durable and washable coverings.
Accordingly, a general aim of the invention is to provide an automatic cutting apparatus and method for cutting piled material, such as velour, made of thermoplastic fibers and which cutting apparatus and method minimizes the amount of dust generating free fibers created during a cutting operation.
Another object of the invention is to provide a cutting apparatus of the foregoing type which does not appreciably interfere with an otherwise conventional cutting operation and which does not degrade the quality of the pattern pieces cut during the cutting operation.